You do not need ETA for this trip.
The duration of your intended stay in Canada has no bearing on the ETA requirement.
ESTA is a US program. ESTA has no bearing on the ETA requirement or on entering Canada in general.
ETA is required when you fly into Canada. It doesn't matter whether you're staying for an hour, a night, or a month. Similarly, as you note, it is not required when you cross the land border, regardless of how long you intend to stay.
If you would require ETA to fly into Canada, you are eligible to cross the land border into Canada without ETA.
Further information is available on the Canadian government's page at https://www.canada.ca/en/immigration-refugees-citizenship/services/visit-canada/eta.html.
(People who would be eligible to fly to Canada with ETA will nonetheless be exempt from ETA if they have certain other documents such as a Canadian visa or residence permit, but that's not particularly relevant to land border crossings.)